Non invasive echographic techniques for arterial wall characterization

The authors´ goal is the definition of new vascular ultrasound modalities for the detection and the characterization of vascular diseases. They propose quantitative approaches for local arterial wall lesions evaluations based on ultrasonic measurements of the wall motion dynamics. A conventional ultrasound scanner is configured to provide a very high frame rate up to 200 frames per second. The arterial segments are axially visualized and the resulting RF signals are cross-correlated from frame to frame for the extraction of wall incremental motions. Wall displacements and intraparietal strain images are reconstructed providing dynamic images sequences. Arterial dilations and wall displacements are dynamically superimposed on the grey scale images. In vitro and in vivo data have been processed in order to test and validate these new procedures. In particular, strain images acquired in vitro on arterial samples are compared with the corresponding anatomo-pathological analysis. Wall displacements measurements are confronted to a mechanical model describing arterial lesions as local defects in elastic tubes. The proposed displays are very attractive to observe the arterial wall behaviour in case of plaques or stenoses. Moreover, the obtained wall motions are in good accordance with the modelized ones. These new ultrasonic procedures dynamically describe the mechanical consequences of arterial lesions. It will probably enable physicians to evaluate vascular diseases with pertinent criteria based directly on the arterial wall state